Wastewater plant undergoing multi-million-dollar upgrades; new diffusers and UV equipment installed

City staff provided a photo-driven update on the wastewater treatment plant renovation, which staff described as the largest project in recent memory at "upwards of $7 million." Jake Renny walked commissioners through installations, inspections and the construction schedule.

Renny explained the new aeration-basin diffusers (black rubber membranes) installed in January; manufacturer representatives must inspect the diffusers to satisfy warranty requirements. He described the membrane function (perforations on the sides and bottom to control air flow), the confined-space nature of the installation and the need for periodic inspection.

Staff also described new compressed-air piping to support an "enviro mix" digester system (Biocycle D) that alternates aerobic and anoxic conditions to improve volatile solids reduction and energy efficiency by allowing intermittent compressor 'burping' rather than continuous aeration. Photo and video excerpts illustrated the concept.

Other work underway includes replacement doors and locks across the facility, recoating and painting of UV channels (channel one startup expected June 1, channel two by July 1), new blowers and VFD drives between July and September, digester upgrades through late summer, and replacement of lift-station pumps and rotary drum thickener in subsequent months.

Commissioners asked biological and operational questions — including which microbes dominate digestion (Renny cited a community of bacteria including E. coli among many organisms) — and probed cost overruns tied to damaged membranes and associated pipe failures. Renny listed anticipated additional capital work (staircase replacements, electrical upgrades, explosion-proof lighting) and estimated project completion percentage at roughly 20% due to equipment lead times.

Commissioners thanked staff for the update and asked staff to 'keep after' the contractor and vendors as the project progresses.